Cubicin

Drug Overview

Cubicin is a cyclic lipopeptide antibacterial that has a unique mechanism of action. It causes rapid depolarization of the bacterial cell membrane potential upon binding to the membrane. The drug ultimately causes bacterial cell death by inhibiting the synthesis of DNA, RNA, and protein due to the loss of cell membrane polarization. Its antibacterial spectrum includes mainly Gram-positive bacteria. It has demonstrated in vitro activity against Staphylococcus aureus, including MRSA. It also has activity against some vancomycin-susceptible Streptococci and Enterococci. Its activity against vancomycin-resistant Enterococci (VRE) has not been fully proven.

Analyst Outlook

Cubicin (daptomycin; Cubist Pharmaceuticals/Novartis/Merck & Co/AstraZeneca) gained its first regulatory approval for complicated skin and skin structure infections (cSSSI) in the US market in 2003. Cubist Pharmaceuticals presented the drug as a convenient once-a-day therapy for cSSSI caused by Gram-positive bacteria including methicillin-resistant Staphylococcus aureus (MRSA). The company has adopted a licensing-focused development strategy to enhance Cubicin’s penetration in the global markets. The drug’s intravenous-only formulation puts it at a clinical disadvantage against some of its competitors. This is exacerbated by the imminent threat of generic competition and the development of pipeline candidates with more convenient dosing options, which threaten Cubicin’s share in the future cSSSI market and subsequently limit the drug’s commercial attractiveness.